Rail steel



" ance to wear of rails,

Patented Sept. 27, 1927.

, U-NITED STA TES PATENT OFFICE.

JOSEPH KENT SMITH, OF DETROIT, MICHIGAN, ASBIGNOR TO 0. HAROLD WILLS, OF

MARYSVILLE, MICHIGAN.

nan. STEEL.

No Drawing.

This invention relates to rail steel, and steel of an analogouscharacter.

The nature, objects, and advantages, of the invention will be bestunderstood from the following: In the last few years, in railroadtransportation, the average speed has greatly increased, as has also theaverage wheel load of cars and of locomotives, in addition to which thevolume of trafiic has greatly increased. Thus, the life strength, andresisthave become increasingly important factors, and the rails now lastso short a time that some railway engineers are contemplating heattreating rail steel in order to increase those physical properties suchas resistance to shock, static strength, and resistance to wear.

However, heat treatment of such articles as steel rails involves a veryheavy additional expense, especially in equipment, and will ordinarilydecrease the tonnage out at of the rail mill. Mere increase in the slzeof the rail certainly will not fulfill all the needs of the situation.

The primary object of the present invention is toprovide a rail steelwhich, among other things, will meet the conditions above specified, andwhich, although not heat treated, will have substantially the sameproperties as though heat treatment were resorted to. i

More specifically I propose to add certain alloying material which willgive to the rail steel the desired physical properties at a much lowercost than would be involved in heat treatment, and this withoutrestricting in any way mill production.

Other objects and advantages will be hereinafter more particularly setforth.

I accomplish the desired results by intensifying-and in extreme cases,perha s, reversingthe potential differential of t e ferrite and carbideconstituents of the steel. To this end I add an alloying ingredient,such as copper, which will dissolve in the ferrite; and I also addanother alloying ingredient, such as molybdenum, which will intensifythe 2 :tion of the copper by the further solid solution of a little ofthe molybdenum. The molybdenum will, in addition, strengthen thecarbides by the oo-formation in them of a molybdenum-complex carbide. Itake every care to avoid the presence, in

Application filed June 22, 1826. Serial No. 117,829.

the carbide, of isolated spots of simple undissociated molybdenumcarbide. I

In consequence, I produce a rail steel which will not deteriorate nearlyas rapidly as standard rail steel. In "this connection, I have foundbeyond question that a strong contributory factor to the rate of wear ofa rail in service is damp atmospheric attack, as it results in thecontinued presentation of fresh disintegrated surfaces, singly perhapsof extreme thinness, to the sweeping and abrasive action of the load.Such dis 'ntegration is counteracted largely by the presence of thecopper in solid solution, the action of which is intensified bymolybdenum. The increase in resistance to shock is primarily due to theemployment of the copper and of. such mol bdenum as is in solidsolution. The moly denum further adds to the general wearing properties,directly increasing the resistance to abrasion of the ferrite itself,and of the complex carbides finely distributed throughout the metal.

Thus, I am enabled to provide a rail steel of approximately normalweight per'yard which has the physical properties requisite to withstandthe heavy service demands" of modern railroad practice, and, at the sametime, has long life, without deviating from the usual mill practice offabrication.

v Further, the correct molybdenum addition brings about the fine grainwhich is so desirable in metals which will most successfully resist wearand impact.

The rail steel'may be made according to.

standard mill practice with a number of further advanta es. Thus, forexample, difliculties inrol ing, due to the nature of section, thereforethe une ual rate of cooling, and consequently di ering structures of thethick-and thin parts, are minimized. The molybdenum makes the steel, inother words, less sensitive to local heat conditions, and greateruniformity of product is obtained. The allowable range within which therollin temperatures must ordinarily be confined is substantially widenedwithout detrimental results, the advantages of which will be obvious tothose skilled in the art.

I prefer to employ a composition substantially as follows: carbon fromabout 35% to about .75%; manganese from about .5% to about 1.1%; copperfrom about 25% to was about 1.25%; molybdenum from about .07

to about 1.0%; and silicon, sulphur and phosphorus as per usualpractice, that is to say, phosphorus not to exceed about .10%; siliconnot to exceed about and sul hur not to exceed about .O6%.

s illustrative of the best practice that I am now aware of for a 120 lb.rail, I would make the steel of the following composition: carbon 58%;manganese .75.%; copper .45%; molybdenum .18%; and silicon, sulphur andphosphorus as usual.

It is to'be understood that my invention is not to be limited to theprecise composition recited, nor to the precise alloying ingredients, asother ingredients may be employed to produce substantially the sameresults in giving an unheat-treated steel the properties above setforth, and such as would be obtained by heat treatment of an otherwisestandard rail steel. For example, I may substitute nickel for some orall of the copper, and may utilize, in part, carbideforming elementslike chromium, vanadium, etc.

I claim:-

1. A rail com osed of non-heat-treated steel of substantially thefollowing composition: carbon from about .35% to .75%; manganese fromabout .5% to about 1.1%; copper from about to about 1.25%; molybdenumfrom about .07 to about 1%; and silicon, sulphur and phosphorus in aboutusual percentages.

2. A rail composed of non-heat-treated steel of approximately thefollowing composition; carbon .58%; manganese .75%; copper. 45%;molybdenum .18 and silicon, sulphur and phosphorus n usual percentages.

In testimony whereof I have hereunto signed my name.

J. KENT SMITH.

